DC to DC power converters are used to convert a DC input voltage provided by a DC power source at a first level to a DC output voltage at a second level.
One example is a neutral forming converter for providing a voltage at a neutral level for an AC load.
Turnbull U.S. Pat. No. 3,775,663 discloses an inverter with an electronically controlled neutral terminal for direct connection to an AC load. Input terminals receive a DC input voltage. A half-bridge inverter is coupled between the input terminals and includes series-connected solid-state switches. A pair of capacitors is coupled between the input terminals and an inductor is coupled between the junction of the solid state switches and the junction of the capacitors. The neutral terminal is coupled to the junction of the inductor with the capacitors. The switches are alternately rendered conductive by closed-loop circuitry to maintain the voltage at the neutral terminal at a neutral voltage.
According to Turnbull, the inductor must be relatively large to minimize ripple current. Due to the large inductor, the switch conduction time must be modified by the closed-loop circuitry to allow the neutral to present a sufficiently low impedance to the load and to load changes.